Edwin bryant thornhill



E. B. THORNHILL.

FLOTATION PROCESS.

APPLICATION FILED MAR. 8. 1918.

1,338,264. Patented Apr. 27, 1920.

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UNITED STATES PATENT OFFICE.

EDWIN BRYANT THORNHILL, '01? OTTAVIA, ONTARIO, CANADA, ASSIGNOR TO THEGENERAL ENGINEERING COMPANY, INCORPORATED, 0F SALT LAKE CITY,

UTAH, A CORPORATION OF UTAH.

FLOTATION PROCESS.

Specification of Letters Patent.

Patented Apr. 27, 1920.

Application filed. March 8, 1918. Serial No. 221,266.

To aZZ whom it may concern:

Be it known that I, EDWIN BRYANT TironNrnLL, a citizen of the UnitedStates, resident of the city of Ottawa, in the Province of Ontario,Dominion of Canada, have invented certain new and useful Improvements inFlotation Processes, of which the following is a specification.

This invention relates to flotation processes, and the objects of theinvention are to adapt such processes to the recovery of the mineralcontents of ores (such as molybdenite) in which certain fine mineralparticles, when freed from their gangue, tend to flocculate or segregatetogether in clusters in preference to other mineral particles. It isusual in flotation processes to produce what is termed a flotationconcentrate, by passing through, or otherwise introducing finely dividedair into a mixture of ground ore, water and oil. With some ores (such asthose containing molybdenite) it is found difficult with this procedurealone to make a flotation concentrate of sufficiently high grade,particularly when treating ores of low mineral contents, or thosecontaining other minerals.

I have discovered that certain minerals, when so treated in a water-oilmixture, will flocculate or coagulate together, while other minerals, orthe gangue that may be pres out, will not; and this property may betaken advantage of to effect a separation of the desirable mineral fromthe gangue, or the other undesirable minerals present, by screening, allcarried out in the manner hereinafter more fully set forth anddescribed.

The process has been especially worked out in connection with molybdenumores, and the present specifications have been written with specialreference to such ores, but it is no doubt possible to extend itsapplication to other ores having the same physical characteristics.

In practising this invention, the ore is first ground to the necessarydegree of fineness, to liberate the minerals, and mixed with an oil or amixture of different oils, and water in the manner usually practisedwith flotation processes. The oil used is preferably some petroleumproduct, such as coal oil, the quantity of which and other technicaldetails being determined by experiment in the manner well known in theart.

The flotation process is then carried on in the usualway to produceultimately, a flotation concentrate, containing a relatively largepercentage of the desirable mineral contents of the ore (molybdenite) ina flocculated form.

To separate this mineral content from the other minerals present, or thegangue, in accordance with the present invention, the flotationconcentrate is then subjected to a screening operation, by which theflocculated mineral (molybdenite) is retained on the meshes of thescreen, and the unflocculated minerals (such as iron or copper pyrite)and the gangue pass through the meshes.

Any suitable type of screen for this purpose may be used andthe-apertures may be varied so as to produce the result desired. On anore crushed to 100 mesh,I have found that an 80 mesh screen is effectivein separating the gcrater part' of the molybdenite, but a finer screen,or even a coarser one, might better suit the requirements in some cases;this being due to the fact that the small particles of the molybdeniteflocculate or coagulate together and remain on the screen, while theparticles of gangue, or the other unflocculatable minerals, passthrough.

The material passing through the screen may be considered as aretreatment product, and be returned back into the original circuit, tobe once again acted upon, or in some cases, may be disposed of in otherways.

The drawings illustrate diagrammatically an apparatus for carrying outthe process. In the drawings, A represents the container for theflotation re-agents. B represents the roughing cell of the flotationapparatus, and 0 represents the cleaning cell of the flotationapparatus, to each of which cells air is forced under pressure from ablower D through suitable perforated air chambers 10 in the bottom ofthe cells. The froth formed on the surface of the roughing cell istransferred by the pump E to the cleaning cell. The froth concentratesfrom the cleaning cell are adapted to pass by gravity to a trough F, andfrom this trough to the top of the traveling belt screen G, from whichthe oversize pass into a bin H.

The undersizc from the screen and tailings from the cell 0 beingreturned by a pump I to the cell B, the tailings from the cell B usuallygoes to waste. It would be understood that both the flotation cells Band C are formed in the manner Well known in the art and which ispractised in the ordinary flotation process.

As many changes could be made in the above process and many apparentlywidely different embodiments of my invention Within the scope of theclaim could be employed without departing from the spirit or scopethereof, it is intended that all mat ter contained in the abovespecification and accompanying drawings, be interpreted as illustrativeand not in a limiting sense.

What I claim as my invention is: The herein described process ofcoagulating certain minerals in preference to others by flotation,screening the resulting concentrates whereby the coagulated mineral isheld on the screen, and the uncoagulated ones pass through, andreturning the same back into the original feed for retreatment. Inwitness whereof I have hereunto set my hand in the presence of awitness.

EDWVIN BRYAN T THORNHILL. lVitness:

RUssEL B. SMART.

